Thursday’s Senate hearing to confirm President Barack Obama’s choice to lead the CIA bared some of the deepest wounds of the more than decadelong war on terrorism and illustrated — at times dramatically — how keenly America continues to feel them.

John Brennan faced rigorous questioning from lawmakers on both sides of the aisle over the most contentious issues in American national security, including harsh interrogation techniques and the secret assassinations of terrorists, and he endured the jeers of protesters who became so rancorous they shut down his hearing.

Lawmakers also pounced on the role Brennan may have played in the release of secrets to the press; the “trust deficit” between the CIA and Congress; and the cloak of secrecy the Obama administration and its predecessor have thrown over their policies on detainees, drones and other matters.

But Brennan vowed that if he’s confirmed, he would keep mindful of the Constitution, the law, the role of Congress and the public interest as he carries out the secret business of a spy agency that sometimes shares the shadows uneasily with its alphabet-soup siblings in the intelligence community and its behemoth cousin, the Department of Defense.

Nonetheless, in a manner perhaps befitting America’s spymaster, Brennan refused to be pinned down on several key questions. When lawmakers pressed him to commit to giving them documents they said were long due from the CIA, he vowed to take their cause to Langley but not necessarily to give them exactly what they wanted. When they pressed him on America’s secret drone strike program, he agreed it should be more transparent and the public should have a more complete understanding, but he did not give many details in Thursday’s open session.

And in one key moment, Sen. Carl Levin (D-Mich.) asked Brennan repeatedly about waterboarding — which the CIA used along with other harsh interrogation techniques in the years after the Sept. 11 attacks. Levin asked Brennan whether he considers that technique torture.

Waterboarding was “something that should have been banned long ago,” he said. But was it torture? “I have personal opinion that waterboarding is reprehensible and it’s something that should not be done,” Brennan said. Defense Secretary Leon Panetta, who previously headed the CIA, has said he believes waterboarding to be torture.

Given Brennan’s views, why didn’t he act to stop what the CIA called “enhanced interrogation techniques” at the time he knew about them?

“I expressed my personal objections to the [enhanced interrogation techniques], waterboarding, nudity and others,” Brennan said, adding that they were “something being done elsewhere in the agency under the authority of others.”

Brennan’s exchanges with senators took place in a hearing chamber with an abundance of empty chairs, left there after repeated protests by the liberal group Code Pink prompted Intelligence Committee Chairwoman Sen. Dianne Feinstein to order Capitol Police to clear the room.

“This witness is entitled to be heard, ladies and gentlemen. So please, give him that opportunity,” the California Democrat told them.A woman who stood on her chair and held a doll yelled: “Mrs. Feinstein, are your children more important than the children of Pakistan and Yemen?”

Feinstein ordered the room cleared and suspended the hearing for about five minutes. When it reconvened, there were few members of the public in the room, and several dozen staffers, security and members of the press.

Before the hearing began, the protesters held signs with slogans such as “Brennan=War Criminal,” “Don’t Drone me, bro” and “Stop Drones Stop Brennan.” Several protesters rushed up to Brennan as he took his seat, unfurling signs and shouting about drone policies.

“Mr. Brennan, congratulations on your nomination. As you can see, it’s going to be lively,” Feinstein joked ahead of her opening remarks.

The drone issue proved contentious even after the protesters were gone. Lawmakers said they wanted more information about how the administration conducts its secret drone attacks in Pakistan, Yemen and elsewhere, and Feinstein went as far as to advocate a new oversight court like the one involved with electronic eavesdropping.

One leading drone skeptic, Sen. Ron Wyden (D-Ore.), zeroed in specifically on the administration’s authority to kill American citizens. When, he asked, does the president have enough evidence to order an American killed without trial and can exercise that authority inside the United States?

Brennan, who gave an unprecedented speech last April about the drone strikes program, did not answer in detail, but he concurred with Wyden that the administration needed to be transparent about the use of drones and he reassured lawmakers about how carefully the CIA employs them.

“I think the American people would be pleased to know that we’re very disciplined, very judicious in how we use these authorities — and we use these abilities as a last resort,” he said.

Neither drone skeptics nor advocates appeared mollified, however. Feinstein, for example, argued the administration’s strict secrecy on drones was counterproductive given how much information had appeared about them in public, and she tried to draw Brennan out about one high-profile target of a drone strike, the U.S.-born Al Qaeda recruiter Anwar al-Awlaki.

Earlier, Feinstein said she was frustrated because she wanted the public to know how effective the CIA has been at minimizing civilian casualties in drone strikes, and said at times the official number she’d received was “in the single digits,” but that the CIA had barred her from disclosing exactly what it was.

But the presence of so much other purportedly secret information about drones and other subjects in the public realm was a sticking point for some members of the panel, who pressed Brennan repeatedly about the role he may have had in press reports about the war on terror. He denied any role in leaks.

“I have never provided classified information to reporters,” he said. “I engage in discussions with reporters about classified issues that they might have had access to because of unfortunate leaks of classified information, and I frequently work with reporters, if not editors to keep out of the public domain some of this country’s most important secrets,” Brennan told the panel. “After working in the intelligence profession for 30 years … I know the importance of keeping those secrets secret.”

However, later in the hearing, Sen. Jim Risch (R-Idaho) said explicitly that Brennan had been responsible for leaking security secrets.

“It seems to me the leak the Justice Department is looking for is right here in front of us,” Risch said during one of the hearing’s most contentious exchanges. Risch referenced the disclosure that a double agent was involved in an Al Qaeda-related airline bombing plot broken up in Yemen last May.

“I disagree vehemently,” Brennan replied, adding that he’d been interviewed by investigators and was told he was just a witness in the case, not a subject or target of the probe.

However, Brennan said leaks about the double agent “should never have happened.

“In my discussion with those individuals that night, it already was out in the press,” he insisted.

Brennan, a Virginia resident, was flanked by and introduced by Sen. Mark Warner (D-Va.)

Warner said Thursday that Brennan’s “long career and public service have prepared him to be the director of the CIA.” He also called Brennan an “advocate for greater transparency” in counterterrorism.

In his opening statement, Brennan pledged to eliminate the “trust deficit” between the agency and the Senate Intelligence Committee.

“During my courtesy calls with many of you, I also heard repeated reference to a ‘trust deficit’ that has, at times, existed between this committee and the CIA. If I am confirmed, a trust deficit between the committee and the CIA would be wholly unacceptable to me, and I would make it my goal on Day One of my tenure — and every day thereafter — to strengthen the trust between us,” Brennan said.

Brennan said he has a “reputation” for speaking his mind and “at times, doing so in a rather direct manner.”

“I like to think that my candor and bluntness will reassure you that you will get straight answers from me,” he said. “Maybe not always the ones you like, but you will get answers and they will reflect my honest views. That’s the commitment I make to you.”

Obama nominated Brennan to replace CIA Director David Petraeus, who resigned from the agency late last year citing an extramarital affair.

Feinstein said the Senate panel would meet with Brennan again on Feb. 12 in a closed session so it could talk about classified matters out of the public view.